#include<bits/stdc++.h>

using namespace std;

int main() {
    for (int n; cin >> n;) {
        vector<vector<char>> a(n, vector<char>(n, ' '));
        for (int i = 0; i < n; i++)
            for (int j = 0; j < n; j++) {
                if (i == 0 || j == 0 || i == n - 1 || j == n - 1)a[i][j] = 'O';
            }
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < n; j++) {
                cout << a[i][j];
            }
            cout << endl;
        }
        cout << endl;
    }

    return 0;
}